Although polyurethane foam production can be described as a mature technology, processing and performance difficulties associated with polyurethane foam continue to be addressed by the industry. Many of these difficulties arise or are exacerbated when processing and/or performance windows are narrow.
For example, the Montreal Protocol, which mandanted the change from chlorofluorocarbons and other halogenated hydrocarbon physical blowing agents to "environmentally acceptable" blowing agents, particularly to the use of water as a reactive blowing agent, created numerous problems, some of which are being addressed even today. The trend to reduced density in products such as soft cushioning foam has also required significant research to enable efficient production of high quality low density foam having the required softness and durability. Recently, hypersoft foam has been increasingly in demand, and its efficient production has required non-traditional processing improvements.
Hypersoft foam may be produced by reacting a di- or polyisocyanate, preferably toluene diisocyanate ("TDI") with a polyol component which includes a high polyoxyethylene content polyol. Thus far, hypersoft foams have also required, in addition, a conventional, high polyoxypropylene-content polyol, in order to be successfully produced. While use of these very different polyols has enabled production of hypersoft foam, the foam processing latitude is often marginal. Moreover, these polyols are not physically compatible, and their blends tend to quickly become inhomogeneous after mixing, requiring inventory of two separate polyols and their separate metering to the mixhead.
It would be desirable to provide a polyol blend which is capable of preparing hypersoft and other polyurethane foams without the necessity of inventorying several polyols for this purpose. It would be further desirable to produce polyol blends which avoid rapid separation during storage, and which offer improved processing latitude when used in preparing hypersoft polyurethane foams.